Three Dimensional Analysis of Intraoral Scanners Accuracy: An In-Vitro Study

Abstract

Purpose: To evaluate and compare the accuracy of two intraoral scanners (IOS) for partial and complete coverage tooth preparations in the presence and absence of adjacent teeth using three-dimensional (3D) comparisons. Materials and Methods: Eight different complete coverage (CC) and partial coverage (PC) tooth preparations were scanned by two IOS, the Trios (TRI) IOS from 3Shape and the True Definition (TRU) IOS from 3M. All teeth preparations were scanned with the IOS in the presence and absence of adjacent teeth. Four groups were established for each scanner; Group 1: PC preparations with adjacent teeth. Group 2: CC preparations with adjacent teeth. Group 3: PC preparations without adjacent teeth. Group 4: CC preparations without adjacent teeth. 3D analysis was performed on scanned preparations using 3D compare software to examine average absolute discrepancy (AAD) and maximum absolute discrepancy (MAD). A Two-way ANOVA was performed followed by a post-hoc Tukey’s test HSD to evaluate the effect of adjacent teeth, preparation design, and the type of intraoral scanner used Results: For TRI IOS, the AAD for Groups 1, 2, 3, and 4 were 20.0±1.8 μm, 19.6±2.4 μm, 15.5±2.7 μm, and 12.9±1.4 μm respectively, whereas the MAD for groups 1, 2, 3, and 4 were 109.7±13.5 μm, 93.2±8.9 μm, 85.6±16.1 μm, and 66.0±11.2 μm respectively. For TRU IOS, the AAD for Groups 1, 2, 3, and 4 were 22.1±3.7 μm, 17.9±2.0 μm, 20.1±5.9 μm, and 14.9±1.8 μm respectively, whereas the MAD for groups 1, 2, 3, and 4 were 130.6±38.5 μm, 92.7±13.5 μm, 89.1±20.4 μm, and 68.0±11.8 μm respectively. Two-way ANOVA showed statistically significant differences between the AAD and MAD of both TRI and TRU IOS (P\u3c .001), as well as the presence or absence of adjacent teeth (P \u3c.001) and preparation design (P\u3c.001). Conclusions: Within the limitations of this study, PC preparation scans exhibited lower accuracy than CC scans. In addition, the presence of adjacent teeth decreased the accuracy of both IOS. Comparable accuracy for CC preparation scans were found for both IOS, with the TRI IOS having better accuracy for PC preparation scans